The present invention generally relates to a system for pressurizing a plurality of vessels and, in particular, relates to a system for pressurizing a plurality of solvent vessels in a liquid chromatographic instrument.
In recent years liquid chromatography systems have evolved such that unattended analysis involves separating a particular sample a number of times but using a different solvent composition, or mixture each time. Alternately, a variety of different samples can be analyzed, each with a different solvent composition. In such systems, in order to enhance the flow of individual solvent components, it is helpful to individually pressurize each solvent container. Thus, when that solvent component is required by the liquid chromatography system the solvent readily flows from the container due to the pressure thereon rather than being flow regulated by a suction created in a piston cylinder. A major advantage to pressurizing the solvent components is that air bubbles, usually found in nonpressurized systems, are eliminated. Consequently, since air bubbles tend to reduce the performance of the solvent pump, the entire liquid flow exhibits an increased efficiency. However, since many solvents are acids or other hazardous materials and since any liquid under pressure is potentially injurious to both equipment and personnel, a number of potential dangers exist in present liquid chromatography solvent gradient systems.
One potential danger exists in the accessibility of the solvents, in particular, when those solvents are pressurized. The conventional approach to avoiding this danger is to provide a simple interlock which locks the access door to the solvent compartment whenever any solvent is pressurized. Unfortunately, most simple interlocks can be simply bypassed or manually overidden.
Another danger exists from system leakage. Leakage of solvent material or the leakage of external air into the system can have serious consequences. For example, the leakage of solvent material, such as an acid, from the system to, say, the laboratory workbench presents a danger to both personnel and equipment. Another consequence of leakage, perhaps of lesser danger to personnel but nevertheless serious, is unequal pressurization among the various solvent containers. Unequal pressurization among the solvent containers generally results in misproportioning of the solvent components in the resultant solvent mixture.
Yet another common problem occurs during sparging, i.e., the degassing of a solvent component by passing helium therethrough. In conventional systems the solvent container, or bottle, is purchased with a valve as a single unit. Hence, each bottle has a valve associated therewith. During sparging it is not uncommon for solvent material to be forced back across the valve and into the system pump. This can seriously impair the accuracy of subsequent measurements since the actual solvent mixture becomes inaccurate and unknown.
In consideration of the above, it is highly desirable to provide a solvent pressurization system which substantially, if not completely, alleviates these dangers.